Emergency Airway Management
Walter Kuhn, M.D., FACEP
Airway skills are perhaps the most important skills that an emergency physician possesses. If the airway is
lost in a critically ill patient for any reason, any of the other interventions you might make, or any great
diagnoses are superfluous. It is good to remember that in the ABC’s of resuscitation, airway is first and
foremost. With the exception of defibrillation in a cardiac arrest situation and possibly a needle
decompression in the patient with a tension pneumothorax, airway control always assumes first priority.
Since the need to protect the airway most often occurs in a crisis situation in the ED, the emergency
physician can not rely on others, like anesthesia, to assist. Even moments of delay can spell disaster for the
patient. Since every airway emergency presents in a different fashion, the emergency physician must be
proficient in multiple techniques to protect and intubate the airway, and must be prepared with all the
necessary equipment to perform these alternative procedures should the initial plan fail.
Indications for Intubation
There are several indications for intubation. The first occurs when the patient is unable to protect or
maintain his/her airway. An example of this might be someone deeply comatose from a head injury or drug
overdose who can not protect his airway from aspiration if vomiting should occur. It has been taught that
the absence of the gag reflex is a reliable method of assessing whether or not the airway is protected. In
fact this might not be the case. Up to 20% of the normal population may not have a gag reflex. A better
assessment of airway protection is evaluation of the ability to swallow spontaneously and handle secretions.
Even if the patient is “breathing on his own” and ventilation is adequate, this does not assure us that the
patient will be protect his airway if vomiting were to occur, and the morbidity and mortality from aspiration
is quite high. The second indication is failure of oxygenation or ventilation as might occur in someone with
asthma, COPD or pulmonary edema. If the PaO2 can not be maintained with supplemental oxygen or such
techniques as BiPAP, the patient will ultimately need ventilation through endotracheal intubation. The
third is an anticipated clinical course that makes airway management imperative. This might include such
patients as those with oropharyngeal burns from a house fire, facial trauma or facial abscesses. Airway
compromise in these conditions is a real possibility and airway management often becomes increasingly
difficult as time passes. If there is an anatomical distortion that will make intubation more difficult as time
goes on, it is the wise physician who will recognize the problem and provide simple protection before the
process progresses.
Once it has been established that airway intervention will be necessary, there are several questions the
emergency physician must ask: How much time do I have? Is this a critical airway and a crash situation?
Do I need to intubate now or do I have a few minutes to prepare? If you are in a crash situation like a full
cardiopulmonary arrest, orotracheal intubation must proceed without further delay. If there is time to
prepare, then the physician must predict which airway intervention is best and most likely to succeed. He
must evaluate whether this will be a difficult airway to intubate and if it is a difficult airway and the first
attempt at intubation fails, can the patient be ventilated with a bag-valve-mask. [If I am unable to intubate
and I can not ventilate with a bag-valve-mask, am I prepared to manage the situation?]
Rapid Sequence Intubation
In most cases, airway management will be amenable to standard practices. “Rapid sequence intubation is
the cornerstone of modern emergency airway management.
Although other techniques, such as blind nasotracheal intubation and intubation using sedation along with
neuromuscular blockade, have been used widely in the past, the superiority of rapid sequence intubation in
terms of success rates, complication rates and control of adverse effects, renders it clearly the procedure of
choice for the majority of emergency department intubations.” (ACEP-Advanced Airway Management)
“Rapid sequence intubation is the virtually simultaneous administration of a potent sedative (induction)
agent and a rapidly acting neuromuscular blocking agent to induce unconsciousness and motor paralysis for
tracheal intubation.” (ACEP- Advanced Airway Management) Although there are no absolute
contraindications for rapid sequence intubation, the presence of a potentially difficult airway requires a
careful assessment and a plan with alternatives should the intubation attempt fail.
Rapid sequence intubation (RSI) consists of a series of discrete steps that are best followed to insure the
greatest success. The patient should first be evaluated for the presence of a difficult airway and the ability
to ventilate with a bag-valve-mask should intubation not be successful. It is obvious that the intubation
should take place in a room that is prepared in advance with all equipment needed for resuscitation should
that be necessary. It is the physician’s responsibility to make sure that all equipment is present and in
working order before proceeding! Although nurses may assure you that everything is in working order, the
physician is ultimately responsible and will be the one to have to handle the problem if some critical
equipment is not functioning or a critical drug is not available.
1. Preoxygenation “Bagging” the patient unnecessarily prior to RSI increases the possibility of
vomiting and aspiration. Critical to the philosophy of rapid sequence is the “no bagging” principle. Preoxygenation is the establishment of an oxygen reservoir within the lungs to permit several minutes of apnea
to occur without arterial oxygen desaturation. Pre-oxygenation not only establishes an oxygen reservoir in
the lungs, but also creates an oxygen surplus in the blood and body tissue protecting from hypoxia. In the
spontaneously breathing patient, administration of 100% oxygen (15 liters of O2 in a non rebreather mask
provides 80-90% oxygen) for 5 minutes prior to using paralyzing drugs allows for approximately 5 minutes
of apnea before the hemoglobin desaturates below 90% in the adult. (It is of note that this is not the case in
a child who has a much lower functional residual capacity and may desaturate after 1 or 2 minutes.) A
pulse oximeter should be used throughout the procedure to allow the physician to gauge the oxygen
saturation. In situations wherein time is more critical and it is not possible to pre-oxygenate for 5 minutes,
a significant pre-oxygenation effect can be obtained by having the patient take 3-5 large capacity breaths on
high oxygen.
2. Pretreatment “Pretreatment” is the administration of medications to attenuate the normal physiologic
and pathophysiologic reflex responses that are caused by airway manipulation and the physical presence of
the endotracheal tube. These are usually medications used to blunt the sympathetic discharge that
accompanies laryngoscopy from insertion of the laryngoscope or manipulation of the airway. Situations
where pretreatment is desirable include 1) conditions where there is increased intracranial or intraocular
pressure, as in a head injured patient; 2) conditions where sympathetic discharge would have deleterious
effects on the heart or cardiovascular system as in patients with coronary artery disease, or in children who
might have bradycardia and hypotension from airway manipulation; and 3) in patients with airway disease,
as in asthma, who might have laryngospasm with airway manipulation. There are also times when it might
be advisable to administer a small defasciculating dose of a competitive neuromuscular blocking agent
three minutes prior to the administration of succinylcholine. Lidocaine (1.5 mg/kg given 3 minutes prior to
intubation) has been shown to suppress the cough reflex and attenuate the increased airway resistance,
which results from bronchospasm caused by irritation of the larynx. It also mitigates the effects on a
potential increase in intracranial pressure. Thus it should be considered in all patients prior to the
administration of a neuromuscular blocking agent who have reactive airway disease or elevated ICP.
Fentanyl (3 micro-gms/kg IV 3 minutes before induction) also attenuates the reflex sympathetic response
to laryngoscopy. Fentanyl has no effect on ICP and will cause some hypotension and may suppress
respiratory effort. However, it is useful in patients who might be adversely effected by an increase in heart
rate or blood pressure. This is especially true in patients with ischemic heart disease, pulmonary edema and
cardiogenic shock and in patients with vascular catastrophes like a AAA, subarachnoid hemorrhage or
thoracic dissection. Defasciculating agents like vecuronium and pancuronium in small, nonparalyzing
doses, given 3 minutes before succinylcholine mitigate against potential increases in intracranial pressure
and should be considered when increased ICP is of concern. Lastly, almost all children should receive
atropine before airway manipulation to mitigate against the bradycardia and hypotension induced from
airway manipulation and laryngoscopy.
3. Paralysis and Induction Approximately 5 minutes after pre-oxygenation has begun and 3 minutes
after pretreatment drugs are administered, a sedative and a neuromuscular blocking agent should be rapidly
administered to induce rapid loss of consciousness and paralysis. This should not be titrated or done
tentatively, but should be done as a push to allow for the full effect of the medication. This provides the
best chance at rapid intubation without the possibility of partial or incomplete paralysis. Succinylcholine is
the drug of choice for almost all emergency department intubations and should be given in a full dose of at
least 1.5 mg/kg IV push. Since there are no complications from succinylcholine in larger than normal
doses, the medication should be “rounded up” and a slightly higher dose given rather than a low dose,
which might not induce full paralysis. A sedative should be given almost simultaneously by IV push. This
usually will be midazolam and care must be taken as midazolam may cause some hypotension. Another
but more expensive drug, Etomidate, is gaining rapid popularity in emergency medicine and eventually
may replace Versed. A few seconds after administration of the neuromuscular blocker and sedative, the
patient will loose consciousness and respirations will cease. Between 20-30 seconds of apnea is almost
universal. Sellick’s maneuver should be applied to the cricoid cartilage to prevent regurgitation of gastric
contents and should be maintained throughout the entire sequence until the endotracheal cuff is inflated. It
should be noted that Sellick’s maneuver is often improperly performed. Most often those doing the
Sellick’s maneuver will press down on the thyroid cartilage instead of the cricoid cartilage. This actually
makes intubation more difficult by pushing the cords posterior and out of visualization of the
laryngoscopist. It also does not protect the airway as the esophagus is not occluded. Pressure on the
cricoid cartilage occludes the esophagus and tilts the cords upward toward the visual axis of the
laryngoscopist.
4. Place the tube Approximately 45 seconds after succinylcholine is administered the patients jaw
should be tested for flaccidity and intubation should be undertaken. Intubation attempts before 45 seconds
and full relaxation are rarely successful. It is hard to wait the full 45 seconds when the patient is apneic. It
is also hard not to want to “bag” the patient when he/she is apneic. However, the full 45 seconds should
pass before the tube is introduced. Remember- we pre-oxygenated the patient, so there is plenty of oxygen
to last for several minutes (usually 5), which is plenty of time to get the patient intubated with minutes to
spare. Intubation can proceed calmly in a non- rushed manner. The success rate should be very high and
approach 99% using this algorithm.
5. Post intubation care Tube placement must be confirmed. One of the most disastrous complications
from RSI is unrecognized esophageal intubations. Proper placement of the tube can be confirmed if the
operator actually saw the tube go through the cords. Otherwise, the best method of confirming tube
placement is by end-tidal CO2 monitoring or aspiration techniques. An end tidal CO2 monitor can be easily
attached to the ET tube and color changes noted. Purple (“problem”) means you are not in the right place.
Yellow (“yes”) means you are in the trachea and CO2 is passing by the monitor. If an intermediate color
(tan) is detected, tube placement should be immediately checked. In a small number of cardiac arrest cases,
no color change may be detected even though the tube is properly placed in the trachea. This is caused by
cessation of carbon dioxide production and delivery to the lungs. If a CO2 monitor is not available, another
test, based upon the knowledge that rigid walled structures (trachea) will hold their shape in comparison to
structures with no support (esophagus) which collapse, may be used. A 30 cc syringe can be attached to the
ET tube and the plunger quickly withdrawn. If there is easy flow of air, you are in the trachea, if there is
resistance, you are probably in the esophagus. Chest x-ray can not confirm tube placement in the trachea as
the esophagus lies directly behind the trachea- placement in either structure will appear the same on the AP
chest film.
Absence of breath sounds over the epigastrium, the presence of breath sounds in the lungs and observation
of the rising and falling of the chest with ventilation are unreliable signs of endotracheal intubation and
should not be relied upon. Pulse oximetry should be used throughout the intubation. Desaturation may
suggest esophageal intubation, but desaturation may be delayed several minutes if the patient was properly
pre-oxygenated. Desaturation may also occur precipitously when precious little time is available to correct
the problem. Therefore, oxygen saturation should not be the only basis used to confirm tube placement.
After tube placement is confirmed, attention must be turned to the long term care of the patient on the
ventilator. Remember that succinylcholine will last only about 6 minutes and a long acting nondepolorizer
such as vecuronium should be administered in full paralyzing doses before the succinylcholine effects
subside. Also, since paralysis does not afford sedation or analgesia, a long acting sedative and or analgesia
should also be administered to make the patient comfortable.
The Difficult Airway
Although the vast majority of emergency airways will go smoothly using the above technique of rapid
sequence intubation, everyone, regardless of experience, is bound to have problems sometime. It is
important to recognize which airways may give you problems before you begin down the road to a possibly
failed airway attempt. It is important to choose the most appropriate technique for each particular airway
situation before disaster occurs. I suggest that several simple questions be asked in every airway situation:
If my intubation attempt does not succeed, will I be able to ventilate the patient with a bag-valve-mask? If
I can not ventilate the patient with a BVM, what should be done next and what is my back up plan? Am I
prepared to provide a surgical airway?
Some estimation of the degree of difficulty of an airway is made possible from the following observation
and simple maneuvers.
Facial hair- facial hair (beards and moustache) in men make it difficult to form a tight seal with a
mask. If you need to provide ventilation with a BVM, you will get an air leak which may prevent you from
providing adequate ventilation. Simply smearing a water soluble lubricant (like K-Y jelly) on the beard
may make bagging easier and more effective.
C-spine mobility- C- spine immobilization makes most airway management more difficult as the
neck can not be extended to provide visualization of the cords on laryngoscopy. It also affects performance
of the Sellick’s maneuver. Some cervical collars will have holes in the front to access the cricoid cartilage
for either a cricothyrotomy or Sellick’s maneuver. In reality, these holes do not provide enough access to
make a real difference. In the C-spine immobilized patient, it is often best to remove the collar and have a
colleague hold in-line stabilization of the head and neck during intubation which makes intubation easier.
It has been said in the past that blind nasotracheal intubation was the airway of choice in the C-spine
immobilized patient. However, the complication rate is higher in blind intubation and the movement of the
C-spine with blind nasotracheal intubation is as much or more than with in line traction. The success rate
for blind nasotracheal intubation is 40-50% compared to nearly 99% with oral intubation combined with
RSI. Another example where the C-spine interferes with intubation is in the patient with arthritis of the Cspine or ankylosing spondylitis of the C-spine. Not only will this interfere with extension of the neck but
the C-spine can actually be fractured if extended.
Mouth opening- an adult with normal TMJ will be able to open the mouth to accommodate 3 or 4
fingers between the incisors. TMJ disease or rheumatoid arthritis may limit mouth opening and thus
oropharyngeal and laryngeal visualization. Rheumatoid arthritis can affect the stability of the atlanto-axial
joint causing subluxation and instability.
Physical characteristics- Patients with small mandibles or receding mandibles have tongues that
will obstruct access to the airway during intubation. All children basically fall into this category as they all
have tongues proportionately larger than their developing mandibles. A good rule of thumb is that if you
can look into the mouth without a tongue blade and visualize the uvula, peritonsillar area and posterior
pharynx easily, you should be able to visualize the larynx on intubation. If you struggle with visualization
of the posterior aspects of the throat before intubation, you will struggle during the intubation. The length
of the neck and the position of the larynx is important.
The larynx in the adult should be at the C5-6 level. A larynx that is higher will be difficult to visualize.
Typically, there should be 2 fingerbreaths between the top of the thyroid cartilage and the base of the neck
in the normal adult.
Teeth- All false teeth should be removed prior to intubation. Large upper incisors may obstruct
visualization of the larynx because they elongate the AP axis of the mouth. Jagged teeth may lacerate
balloons on the ET tubes. [If the patient can eat an apple through a picket fence - you are in for trouble.]
Oral dimensions- patients with narrow facial features and high arched palates may have difficult
airways. Access will be limited because of reduced space side to side in the mouth.
The Failed Airway
Although none of us wants to be in a “failed” airway situation, it will happen eventually to all of us. There
are basically 2 scenarios, 1) can’t intubate but can ventilate with a BVM or 2) can’t intubate and can’t
ventilate. In the first situation, one is at least able to maintain reasonable ventilation and oxygenation.
However, the risk of aspiration increases as bagging continues. Even with adequate Sellick’s maneuver,
some air will leak into the stomach causing gastric distension and eventually vomiting. The second
situation is more desperate and if a decision is not made in seconds, the patient will die. Usually this
involves one of two possibilities depending on time. The first is the creation of an immediate surgical
airway either by cricothyrotomy, or percutaneous transtracheal jet ventilation. If you do not have the
transtracheal jet ventilation already set up before hand, you can not use this as you will NEVER be able to
assemble the equipment in time to save the patients life. Neither of these options are viable in the pediatric
patient and surgical airways should not be undertaken in children below the age of puberty! The second
possibility is to use an airway adjunct. Obviously you need to have access to these adjuncts before the
crisis arises. Adjuncts include the Combitube©, laryngeal mask airway, fiberoptic laryngoscopically
assisted intubation, lighted stylette intubation, retrograde intubation using a cricoid puncture technique and
wire, digital intubation and others. The success rates are dependent on availability of the equipment and
operator training and experience. The time to plan for a failed airway is now, not in the crisis of the
moment when it happens. The patient will pay for your lack of preparation!
Special Airway Considerations
The Pediatric patient- the principles of airway management in children are the same as in the
adult. Confusion and error occur when we try to think about the pediatric airway as “different” than the
adult airway. It is just not so! It is true that the dosages of medications are different, we just need to
remember the doses in milligrams per kilogram or look them up. The anatomy is slightly different with
larynx being somewhat anterior and superior to that of the adult and surgical airways are not recommended
in children (The anatomy of the adult larynx is actually more variable than the child’s). With these two
exceptions the pediatric airway should be approached in exactly the same way as the adult airway.
Medications used for children to facilitate intubation and the need for alternative airway techniques in the
case of a failed airway are no different than in the adult.
One concern in the pediatric airway is that the functional residual capacity is lower in the child and preoxygenation will not “buy” you as much time to intubate. With good pre-oxygenation in the adult, an adult
can remain apneic for up to 5 minutes without significant oxygen desaturation. The child may desaturate in
1 minute or less. This is easily overcome by applying Sellick’s maneuver and briefly bagging the patient.
During intubation, atropine is almost universally used in children during the pre-treatment phase (3 minutes
before intubation) to blunt the bradycardia and hypotension that occurs when the larynx is manipulated.
Also, a defasciculating dose of a nondepolorizer is almost never needed in children.
The Trauma Patient- The debate over which technique for intubation is safest in the cervical
spine injured patient has been raging. Blind nasotracheal intubation was commonly used in the 1980’s but
has fallen out of favor because of the high complication rate, high miss rate, stimulation of intracranial
pressure and lack of protection of the C-spine. Recently, there is evidence indicating that with properly
performed rapid sequence intubation and orotracheal intubation with in-line stabilization, there is little
hazard to the patient. Since this affords the best opportunity to intubate with the least risk of a failed
airway, RSI with in-line traction stabilization is now being recommended even in the presence of a cervical
spine injury. Alternatively, if the patient has a proven C-spine injury and an incomplete neurologic deficit
and does not need urgent intubation, then fiberoptic assisted orotracheal or nasotracheal intubation can be
performed by those with experience in this technique in a more leisurely fashion.
The choice of which neuromuscular blocking agent to use for RSI is also controversial. Most
emergency physicians prefer succinylcholine over the longer acting nondepolarizing agents. This is
ultimately safer in a failed airway or a “can’t intubate-can’t ventilate” situation as the neuromuscular
blockade will last only a few minutes. The principal disadvantage of succinylcholine in trauma is its
propensity to cause profound hyperkalemia in some situations. This occurs in burns, crush injuries and
denervation processes like stroke or paralysis. However, the hyperkalemic effect does not occur for days to
a week after injury and should not be a problem in the acutely injured patient.
Succinylcholine will also increase intracranial pressure, which is a concern in many traumatized patients.
This can be mitigated by the use of a small dose of a competitive neuromuscular blocking agent in the
pretreatment phase- for example 1 mg of Norcuron© 3 minutes before the succinylcholine. Lidocaine
should also be used in head injured patients to protect from the rise in BP associated with tracheal
stimulation.
In the patient with a distorted airway either from facial fractures or a neck hematoma, the “wait
and see” approach will only guarantee a more difficult airway in the future. Most authors now recommend
an aggressive approach to the distorted airway with early intubation before the situation becomes more
dangerous. Waiting for the nearly obstructed airway to become completely obstructed can be disastrous.
The distorted airway always disquiets us, as it should. This is one case where the intubationist should plan
ahead and have several options before beginning. Although RSI is not contraindicated, the optimal
approach will probably be an awake intubation with the patient protecting his/her own airway as long as
possible. A combined approach is sometimes also a good option. A little sedation can be used for a quick
look for the glottis. If the glottis can be visualized, RSI can proceed. If the glottis can not be visualized,
another approach must be entertained or a surgical airway anticipated.
The Patient with Increased Intracranial Pressure- Increased intracranial pressure presents a
direct threat to the viability of the brain. Many of the techniques used in airway management may further
increase pressure thus compounding the problem. The use of a laryngoscope to visualize the larynx causes
a release of catecholamines causing increased BP and pulse- both of which are deleterious to the patient
with increased ICP. There may also be a direct increase in ICP not related to tracheal stimulation of
unknown etiology. The ICP will also be increased by the use of succinylcholine as a paralyzing agent.
Although RSI remains the technique of choice in patients with increased ICP and succinylcholine remains
the drug of choice, there are several special considerations.
Several pharmacologic agents mitigate against this increased ICP. The administration of fentanyl, a
synthetic opioid, can blunt the affect of the catecholamine release as will a beta blocker (not often used).
Fentanyl could and should be used in almost all patients with an increased ICP but may cause transient
hypotension and premature apnea in some patients at 3 micrograms/kg dose in the pretreatment phase.
Lidocaine in a dose of 1.5 mg/kg will blunt the reflex response to intubation and should also be used in the
patient with elevated ICP in the pretreatment phase. The increase in ICP related to succinylcholine is
temporally related to the muscle fasciculations and can be avoided by use of a competitive neuromuscular
blocking agent at 1/10th the paralyzing dose in the pretreatment phase. Since ketamine increases cerebral
blood flow, this agent should be avoided in the patient with increased ICP.
The Patient with Asthma or COPD- Always remember that if the patient can’t breath secondary
to reactive airway disease, you might not be able to breath for them either! These patients can be extremely
difficult to ventilate and be hemodynamically unstable. First and foremost there should be aggressive
therapy to “break” their asthma or COPD attack. Use of multiple standard agents as well as Heliox®,
magnesium, anticholinergic agents, and BiPAP and less standard methods may be attempted before
intubation. Asthma is a unique situation in which one MUST intubate the patient on the first try because
often the patient can not be successfully bagged because of the high airway pressures. If the patient needs
intubation, RSI is the best choice. However, the patient should be left in the sitting position until after the
paralyzing medication, succinylcholine, is administered. Although succinylcholine is known to release
histamine, this effect does not appear to be clinically significant. All patients with reactive airway disease
should receive lidocaine in the pretreatment phase to attenuate the respiratory response to airway
manipulation. Ketamine is the induction agent of choice as it has a direct effect on relaxation of bronchial
smooth muscles and should be given just prior to succinylcholine.
Reference
Advanced Emergency Airway Management Walls RM, Luten RC, Murphy ME, Schneider RE. Published
by ACEP, 1997